Re: Estimating water quality


"Jo Schaper" <joschapern4ospam@xxxxxxxxxxxxxxxxx> skrev i en meddelelse
news:125epejia3uvtce@xxxxxxxxxxxxxxxxxxxxx
Carsten Troelsgaard wrote:
I ask becourse my childhood luggage (my father was a gardener &
fliefisher) says that the long swaying algae (local name:SheepTails)
signifies a lower waterquality - this may not exactly be what's at the
pictures, in any case it's at odds with the fact that it's swaying in
non-poluted water welling out from cracks in the chalk (catchment area
largly woodland)

Carsten

I concur with George that you have an algal bloom. The green stuff doesn't
bother me quite as much (like he says, it can be seasonal)as the brown. If
the green is there year round in a spring, you have a nutrient
problem--such algae are common in degraded surface streams, but assuming
your groundwater is colder than mine (13C) you shouldn't be getting this
much gunk in a spring.

The spring used to produce ~120 l/sec. It's welling out of the ground a few
tens of meters from my underwater foto of the algal forest. The temperature
is ~stabil year round, a few degrees above zero. The algae are not a bloom
but an all year occurrence.
My gut feeling is that ... too much gunk. But my gut feeling isn't worth
much. I will not rely on a vague childhood memory of a different flora, but
you may say that that's what makes me suspicious.

Depending on the spring, recharge can be coming from tens of kilometers
away--

These distances will be needed. The second largest forest of dk covers the
catchment-area. Maybe I should try to make a calculation of how large a
catchment is involved - it's probably larger than I suspect. Within a few
kilometers atleast four springs the size of this one discharges into the
river.

or it may be as simple as a single malfunctioning septic field or cattle
lot upstream, or a pulse of fertilizer which got sent underground through
the system.

It only takes a pee to reduce a first class water to the next class. It
takes more to spoil the next. You wouldn't believe that the other side of
the valley accidentally got 1.000.000 l of gylle (dung) this week. The
'system' got working and no dead fish was registered (I don't know about
chemical measurements) - that's impressive (leaving out worries of longer
term effects).

Two points:

1) knowing some basic biology is good for rough estimating water quality
without testing, but these are only indicators that the water is not of
highest quality. A spring can be crystal clear and lethal, too. As one
local hydrogeo says, "If plants won't grow in it, would YOU drink it?"

If it's a spring and it's clear, I probably would - depending on it's
location.

2) Doing a full spectrum water quality does take a pretty penny, but if
you do a lot of testing, you don't need health department microdecimals
on your answer, and you have a clue what you might find and what data you
suspect (why test for silica if you are looking for nitrate?) some of the
field test kits (Hach kits, Lamotte kits) are pretty cheap but reasonably
accurate. I cannot afford a full kit of research level instrumentation,
however, there are pH meters, DO meters (look in sporting goods),
conductivity meters, etc. for quite reasonable prices.
www.forestry-suppliers.com, www benmeadows.com etc.

I'll have this in mind. The springs are probably well tested, but I'm not
sure weather the figures are public. Whatever, the water has a high quality,
and there's definately no reason for alarm (on this side of the valey) - you
know .. the sentiment that that you can touch something absolutely unspoiled
and original.

Carsten


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